The present invention relates to a resin-made holding member made up of a spring and a holder for holding the spring which are integrally formed into one piece and a toner cartridge using the resin-made holding member.
A metallic coil spring installed in the resin-made holder is often used as the holding member that uses an elastic force for holding. FIGS. 5(a) and 5(b) show an example of the holding member using such a metallic coil spring. When manufacturing such a holding member, it is necessary to install a metallic coil spring on the resin-made holder. A member of smaller size adversely affects the productivity because of the time and labor required for installation. This problem has been left unsolved in the conventional art.
To solve this problem, efforts have been made to study the art of using a resin-made spring from the viewpoint of improving the productivity. One of the technologies based on a resin-made spring is found in the art of related to a dispenser such as shampoo container using a spring called the return spring made up of a plurality of elastic pieces integrally combined with one another, each piece having a restoring force (e.g., Patent Document 1).
However, the shape of the elastic pieces constituting the spring having been disclosed in the Patent Document 1 has been examined by the present inventors, and the following has been found out. The wall thickness on both ends of the piece to which the greatest force is considered to be applied at the time of contraction is smaller than those of other parts. If used for a long period of time, this portion is considered to be easily damaged. As described above, the resin-made spring disclosed in the Patent Document 1 has failed to give consideration to the fact that the spring should not be damaged even when constantly subjected to loads for a long period of time.
[Patent Document 1] Japanese Utility Model Application Publication No. 7-40514